Efficient fertilizer and enzyme-assisted method of production

ABSTRACT

Slow-release fertilizer is produced by composting animal manure with a magnesium-rich compound The temperature of this mixture is maintained at 20-30° C. and the pH is maintained between 7-10. Urease is added to the mixture. Next, the mixture is inoculated with bacteria of the species  Bacillus sphaericus, Bacillus globisporus,  or  Bacillus fusiformis.  The mixture is then allowed to incubate for about 14 days to form magnesium ammonium phosphate. Optionally, phosphatase, an enzyme promoting the formation of phosphate from phosphorus-rich organic compounds, is added with the urease enzyme to increase the yield of magnesium-ammonium phosphate.

GOVERNMENT INTEREST STATEMENT

[0001] The invention described herein may be manufactured, licensed andused by or for governmental purposes without the payment of anyroyalties thereon.

I. BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to an improved process for producing aslow-release fertilizer from animal waste. Specifically, it relates to aprocess for composting animal manure with a magnesium-rich compound andselected enzymes that form ammonia from urea and uric acid, andphosphates from phosphate-rich organic compounds. In addition, bacteriaselected from guano fertilizer may be incorporated with theenzyme-manure mixture to form magnesium ammonium phosphate.

[0004] 2. Prior Art

[0005] The formation of ammonium magnesium phosphate hexahydrateassisted by bacteria has been reported by Nabil Ben mar et al.,Chemosphere, vol. 36, No. 3, p 475-481, (1998). The removal of phosphatefrom supernatant liquors from anaerobically digested sludge by formationof struvite (magnesium ammonium phosphate) is reported by Battistoni etal., Wat. Res., Vol. 31, No. 11, pp. 2925-2929, 1997 The formation ofstruvite by Azobacter in chemically defined media has been described byRivadeneira et al., Microbiol. 30, 55-57 (1985). However, there isnothing in the prior art disclosing the use of enzymes in combinationwith bacteria to produce slow release magnesium-ammonium phosphatefertilizer. The combination of enzymes and bacteria in accordance withthis invention accelerates the production of crystalline magnesiumammonium phosphate and increases its yield. The advantages of thepresent invention over the prior art will be fully appreciated byreading the following description.

II. SUMMARY OF THE INVENTION

[0006] The present invention provides a process for producingslow-release fertilizer from animal manure by composting it with amagnesium-rich compound or a solution of a water-soluble magnesium salt.

[0007] The animal manure is mixed with a magnesium compound or anaqueous solution of magnesium salt. The temperature of this mixture ismaintained at 20-30° C. and the pH is maintained between 7-10. Urease isadded to the mixture. Next, the mixture is inoculated with bacteria ofthe species Bacillus sphaericus, Bacillus globisporus, or Bacillusfusiformis. The mixture is then allowed to incubate for about 14 days toform magnesium ammonium phosphate. Optionally, phosphatase, an enzymepromoting the formation of phosphate from phosphorus-rich organiccompounds, is added with the urease enzyme to increase the yield ofmagnesium-ammonium phosphare.

III. DETAILED DESCRIPTION OF THE INVENTION

[0008] Animal manure is mixed with a low water-solubility of magnesiumcompound or an aqueous solution of a magnesium salt. Magnesiumcarbonate, magnesium hydroxide, in the amount of at least 1.7 parts perpart of nitrogen in the manure, is added to the animal manure. Highlywater-soluble magnesium salts such as magnesium chloride and magnesiumsulfate may also be used, but their dosage must be carefully controlledso as to prevent high osmotic pressure of salts which may kill thebacteria. Magnesium sulfate has the additional disadvantage thatsulfides or mercaptans may be generated, which have an offensive odorand which may discharge toxic air emissions. Magnesium carbonate andmagesium hydroxide provide alkaline buffering to prevent the magnesiumammonium phosphate from being dissolved after it forms.

[0009] The temperature of this mixture is adjusted to 20-30° C. andmaintained in this temperature range. The pH is adjusted to 7-10 byaerating or addition of an acid. Enzymes such as urease are added to themixture at a dosage of about 0.5 mg of bean sprout urease per liter ofmixture. Jack Bean urease Type IX at 62,100 units per gram is suitable.Another suitable material is marketed by Worthington BiochemicalCorporation, Lakewood, N.J. The solid enzyme is mixed with 0.1 molarphosphate buffer to bring the enzyme into solution.

[0010] Next, the mixture is inoculated with bacteria of the speciesBacillus sphaericus, Bacillus globisporus, or Bacillus fusiformis whichare isolated from guano. Commercial guano can also be used. The mixtureis allowed to incubate for about 14 days at 25 to 30° C. to formmagesium ammonium phosphate.

[0011] In an alternate embodiment of this invention, a phosphataseenzyme is added to the batch along with the urease. Typically, analkaline phosphatase such as bovine alkaline phosphatase (RocheMolecular Biochemicals) is used. This enzyme is added at a dosage of 50ml of bovine alkaline phosphatase at a concentration of 1000units/microliter to one liter of manure. The enzyme is blended in withthe manure immediately after the addition of the urease and before theaddition of the bactertial inoculation

[0012] While there have been shown and described what are considered atpresent to be the preferred embodiments of the present invention, itwill be appreciated by those skilled in the art that modifications ofsuch embodiments may be made. It is therefore desired that the inventionnot be limited to these embodiments and it is intended to cover in theappended claims all such modifications as fall within the true spiritand scope of the invention.

We claim:
 1. A process for producing slow-release fertilizer from animalwaste comprising the steps of: (a) mixing the animal waste with awater-soluble magnesium salt; (b) adjusting the pH of the mixture from(a) to between 7 and 10; (c) adding urease enzyme to the mixtureresulting from (b); (d) inoculating the mixture resulting from (c) withbacteria; and (e) maintaining the mixture resulting from (d) at 25-30°for about 14 days; whereby magnesium ammonium phosphate is formed. 2.The process in accordance with claim (1) wherein the water-solublemagnesium is selected from the group consisting of magnesium carbonateand magnesium acetate.
 3. The process in accordance with claim (1)wherein the mixture resulting from step (c) is inoculated with bacteriaselected from the group consisting of the group consisting of Bacillussphaericus, Bacillus globisporus, and Bacillus fusiformis.
 4. Theprocess in accordance with claim (1) further comprising the step ofadding a phosphatase enzyme to the mixture.
 5. The process in accordancewith claim (1) further comprising the step of adding a urease enzyme tothe mixture.
 6. The process in accordance with claim (1) wherein theadjustment of pH in step (b) is accomplished by aeration of the mixtureresulting from step (a).